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BlueMUSE science

An overview of the science cases is presented in the BlueMUSE White paper, available here for download.

BlueMUSE , designed as a sister instrument to MUSE, is an integral-filed spectrograph (IFS) covering one squared arcmin field-of-view (FoV) and capable of accessing the blue wavelength range (350- 580nm) observable from the ground. It will work within the concept of “spectroscopy of everything”, providing a spectrum for any object with the FoV. Observational astronomy in the optical/near infrared wavelengths of the next decade will be characterised by large-scale projects focusing on imaging surveys of the sky: Euclid, Rubin/LSST and Roman. They will provide an unprecedented number of targets and events that will require spectroscopic follow-up.

BlueMUSE is envisioned both as a “discovery” and a “follow-up” instrument. In the former role, through its “spectroscopy of everything” approach, it will provide targets to other instruments to be observed at higher spatial resolution, greater depth or at other wavelengths. In the latter role it will provide spectroscopic coverage in the blue of extended regions on the sky (or large numbers of targets). BlueMUSE will both open up a new range of galactic and extragalactic science cases, and offer a strong synergetic potential for instruments at the ELT.

BlueMUSE, with its blue spectral coverage, larger spaxels and similar FoV to MUSE, will be a complementary and even more powerful facility for spectroscopic observations of deep extragalactic fields. With the blue optimised spectral range, BlueMUSE will target the z~2-4 range (reaching the so-called ‘Cosmic Noon’) where surface brightness is enhanced by a factor ~ 4 in the cosmological surface brightness dimming is a factor of ~4 lower in comparison to z~3-5 surveyed with MUSE. This will provide a similar gain in the ability of BlueMUSE to detect emission from diffuse gas around galaxies, enabling the detection of the emission all the way out into the intergalactic medium (IGM).

Figure 1. Pseudo-colour images of three MUSE deep fields (Bacon et al. 2023). BlueMUSE will be able about 16 times more efficient in observing such deep fields at 2<z<3 due to lower cosmological surface brightness dimming compared with MUSE (covering 3<z<5).

BlueMUSE science cases are split in three groups, mapping astronomical objects and processes from the Solar System to the Distant Universe. Each group is led by a Key Science Case, which is uniquely adapted to BlueMUSE. In addition, there are several more general science cases that strongly benefit from BlueMUSE characteristics and design. The following list in not exhaustive, but presents a selection of science cases that demonstrate the properties of BlueMUSE, its versatility and capability to address the challenges of astrophysical research in 2030s.

A more in-depth overview of the science cases is presented in the BlueMUSE White paper. The latest version of this document updated by the BlueMUSE consortium at the end of Phase A (March 2025) is available [here].
BlueMUSE science preparations are assisted with the BlueMUSE Exposure Time Calculator and with development of BlueSi, an end-to-end simulator software of realistic BlueMUSE (and MUSE) data cubes. More information about the software and its usage can be found on BlueSi pages.